CN107359068B

CN107359068B - Moulded case circuit breaker with compound arc extinguishing performance

Info

Publication number: CN107359068B
Application number: CN201710727710.8A
Authority: CN
Inventors: 张珂; 张信明
Original assignee: Hebei Bao Kay Electric Co ltd
Current assignee: Hebei Bao Kay Electric Co ltd
Priority date: 2017-08-23
Filing date: 2017-08-23
Publication date: 2020-05-22
Anticipated expiration: 2037-08-23
Also published as: CN107359068A

Abstract

A molded case circuit breaker with composite arc extinguishing performance comprises a static contact, a moving contact and an insulating arc extinguishing device, wherein the static contact is installed in a casing, the moving contact is connected with a tripping mechanism, the insulating arc extinguishing device comprises a magnetic yoke, an armature, an insulating shielding plate, a swing rod and a supporting seat, the magnetic yoke and the supporting seat are fixed on the static contact, and the supporting seat is positioned below the magnetic yoke; the insulation shielding plate is positioned on one side of the static contact and corresponds to a gap between the static contact and the movable contact; the upper ends and the lower ends of the swing rod and the magnetic yoke are respectively rotatably connected with the insulation shielding plate and the supporting seat, the swing rod, the armature, the insulation shielding plate and the supporting seat form a four-bar structure, and a torsion spring is arranged between the armature and the supporting seat. The insulating shielding plate can be quickly inserted between the moving contact and the static contact when the breaker breaks the short-circuit current, so that the electric arc between the moving contact and the static contact is extinguished, the amplification time of the electric arc energy is shortened, the short flashover or no flashover of the breaker is realized, and the capacity of the breaker for breaking the short-circuit current is greatly improved.

Description

Moulded case circuit breaker with compound arc extinguishing performance

Technical Field

The invention relates to a molded case circuit breaker with strong short-circuit current breaking capacity, and belongs to the technical field of emergency protection devices.

Background

Plastic case circuit breakers (MCCBs) are important electrical components in industrial and domestic low voltage distribution equipment, and are often used as branch switches of low voltage distribution systems to protect distribution lines from overload and short circuit faults. The short-circuit fault protection is the most important function, and because the short-circuit current of a line is very large during short-circuit fault, plasma electric arcs with very large energy can be generated between a moving contact and a static contact of the breaker when the breaker breaks the short-circuit current, and the breaker can complete the task of breaking the short-circuit current only by quickly extinguishing the electric arcs through certain technical measures.

At present, the MCCB at home and abroad adopts an arc extinguishing chamber technology to cool and extinguish the high-temperature and high-voltage electric arc generated when the short-circuit current is cut off, and the arc extinguishing principle of the technology is as follows: when the short-circuit current is cut off, after the electric arc is generated between the moving contact and the static contact and is stretched to a certain length and the energy is correspondingly amplified, the high-energy electric arc is driven to enter the arc extinguish chamber by adopting magnetic field electrodynamic force or other modes, so that the high-energy electric arc is extinguished under the cooling action of the metal grid sheet in the arc extinguish chamber. The arc extinguishing effect of the method is influenced by factors such as arc extinguishing chamber materials, contact opening speed, contact opening distance, contact materials and the like, particularly for the circuit breaker with a single-breakpoint structure, the capacity of breaking short-circuit current is poor, generally not exceeding the alternating current 400V and 50kA, and the direct-current short-circuit current is not easy to break due to the fact that a zero-crossing process does not exist.

With the construction and development of a power grid and the improvement of the reliability requirement of people on the power grid, a new arc extinguishing scheme is objectively needed to greatly improve the capacity of breaking the short-circuit current of the MCCB.

Disclosure of Invention

The invention aims to provide a molded case circuit breaker with composite arc extinguishing performance aiming at the defects of the prior art so as to improve the breaking capacity of short-circuit current.

The problem of the invention is realized by the following technical scheme:

a molded case circuit breaker with composite arc extinguishing performance comprises a fixed contact, a movable contact and an insulating arc extinguishing device, wherein the fixed contact is installed in a casing, the movable contact is connected with a tripping mechanism, the insulating arc extinguishing device comprises a magnetic yoke, an armature, an insulating shielding plate, a swing rod and a supporting seat, the magnetic yoke and the supporting seat are fixed on the fixed contact, and the supporting seat is located below the magnetic yoke; the insulation shielding plate is positioned on one side of the static contact and corresponds to a gap between the static contact and the movable contact; the upper ends and the lower ends of the oscillating bar and the armature are respectively rotatably connected with the insulation shielding plate and the supporting seat, the oscillating bar, the armature, the insulation shielding plate and the supporting seat form a four-bar structure, and a torsion spring is arranged between the armature and the supporting seat.

According to the molded case circuit breaker with the composite arc extinguishing performance, the insulating gasket is arranged between the magnet yoke and the static contact.

According to the molded case circuit breaker with the composite arc extinguishing performance, the two sides of the insulation shielding plate are bent downwards, one end, far away from the magnetic yoke, of the bent portion is rotatably connected with the armature, and one end, close to the armature, of the bent portion is rotatably connected with the swing rod.

Above-mentioned moulded case circuit breaker with compound arc extinguishing performance, the pendulum rod sets up two, and the both sides at insulating shield board and supporting seat are installed to the two symmetry.

Above-mentioned moulded case circuit breaker with compound arc extinguishing performance, still be equipped with the explosion chamber in the circuit breaker shell.

The insulating shielding plate can be quickly inserted between the moving contact and the static contact when the breaker breaks the short-circuit current, so that the electric arc between the moving contact and the static contact is extinguished, the amplification time of the electric arc energy is shortened, the short flashover or no flashover of the breaker is realized, and the capacity of the breaker for breaking the short-circuit current is greatly improved.

The invention adds the insulation shielding plate as an auxiliary arc extinguishing mechanism, the auxiliary arc extinguishing mechanism can rapidly act at the moment that the breaker breaks the short-circuit current and is inserted between the moving contact and the static contact, and the electric arc just generated between the moving contact and the static contact is extinguished or reduced, so that the amplification time of electric arc energy is shortened, the concentration of electric arc energy is reduced, and the short flashover or no flashover of the breaker is realized. The invention adopts two-stage arc extinction, and the electric arc after the initial auxiliary arc extinction can be introduced into the arc extinction chamber to continue the subsequent arc extinction operation, thereby greatly improving the arc extinction capability of the circuit breaker and greatly improving the short-circuit current breaking capability of the circuit breaker.

Drawings

FIG. 1 is a schematic diagram of the closing state of the present invention;

FIG. 2 is a schematic view of the repelling state of the present invention;

FIG. 3 is a schematic diagram of the opening state of the present invention;

FIG. 4 is a schematic diagram of the structure of the insulated arc extinguishing device;

fig. 5 is a schematic structural view of a stationary contact;

FIG. 6 is a schematic view of the structure of the dielectric shield;

FIG. 7 is a left side view of FIG. 6;

FIG. 8 is a schematic structural diagram of a swing link;

FIG. 9 is a left side view of FIG. 8;

fig. 10 is a schematic structural view of the armature;

fig. 11 is a left side view of fig. 10.

The list of labels in the figure is: 1. static contact; 2. a moving contact; 3. a magnetic yoke; 4. an insulating shield plate; 5. an armature; 6. a torsion spring; 7. a swing rod; 8. a supporting seat; 9. an insulating spacer; 10. a magnetic protection release; 10-1, a tripping mechanism; 11. a screw; 12. a housing; 13. an arc extinguishing chamber; 14. a handle; A. a moving contact rotating shaft; B. an upper pin shaft; C. and a lower pin shaft.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

The invention installs an insulating arc-extinguishing device driven by electromagnetic force at the static contact position of the original MCCB, when the short-circuit fault current occurs on the circuit and the moving and static contacts of the circuit breaker are repelled by the electric repulsion force, the insulating arc-extinguishing device with the four-bar structure acts under the electromagnetic driving action, and the insulating shielding plate is rapidly inserted between the moving and static contacts to play the role of rapidly extinguishing the arc.

Referring to fig. 1-11, the invention comprises a static contact 1, a moving contact 2, a magnetic protection release 10, a tripping mechanism 10-1, an insulating arc-extinguishing device and an arc-extinguishing chamber 13 which are arranged in an engineering plastic shell 12. The insulating arc extinguishing device is of a four-bar structure and mainly comprises a magnetic yoke 3, an insulating shielding plate 4, an armature 5, a torsion spring 6, a swing rod 7, a supporting seat 8 and an insulating gasket 9, the insulating shielding plate 4, the armature 5, the swing rod 7 and the supporting seat 8 form a four-bar mechanism, the supporting seat 8 is fixedly connected with a static contact 1, the swing rod 7 is hinged between the supporting seat 8 and the insulating shielding plate 4 through a pin shaft, the armature 5 is hinged between the supporting seat 8 and the insulating shielding plate 4 through a lower pin shaft C and an upper pin shaft B, and the insulating shielding plate 4 can be inserted between a moving contact and a static contact of a circuit breaker. The magnetic yoke 3 is in a cuboid shape and is installed in the static contact, the upper part, the lower part and one side surface of the magnetic yoke 3 are isolated from the contact part of the static contact by the insulating gasket 9, the magnetic yoke 3 can attract the armature 5 when short-circuit current occurs, and the magnetic yoke also plays a role in supporting the static contact at ordinary times. Normally, the insulating arc-extinguishing device is in an open state due to the action of the torsion spring 6, the armature 5 being in a position away from the yoke 3. However, when a fault short-circuit current occurs in the circuit, because the straight section of the static contact 1 and the current direction of the moving contact 2 are opposite, an electric repulsion force is generated to repel the static contact 1 and the moving contact 2, meanwhile, because the magnetic yoke 3 generates a large attraction force to the armature 5 after being magnetized by a magnetic field generated by the short-circuit current, the armature 5 overcomes the elasticity of the torsion spring 6 to generate rotation, so that the insulating arc-extinguishing device with the four-bar structure is driven to act, and the insulating shielding plate 4 of the insulating arc-extinguishing device is rapidly inserted between the moving contact 2 and the static contact 1 while the moving contact and the static contact are repelled (or while being opened by a short-circuit instantaneous release), thereby playing a. Meanwhile, the short-circuit instantaneous release of the switch acts, so that the MCCB finishes the breaking process. As the short-circuit current is cut off, the strong electromagnetic field disappears, and the insulation shielding flashboard returns to the original position under the action of the torsion spring.

The insulation shielding plate 4 is made of high-strength and high-temperature-resistant engineering plastic materials. The number of times (3 times at most) of effectively breaking the short-circuit current specified by the product standard can be ensured.

The insulation shielding plate 4 is used as an auxiliary arc extinguishing mechanism for extinguishing arc when the moving contact and the static contact are not completely opened, and the common arc extinguishing chamber has a good residual arc extinguishing effect after the moving contact and the static contact are completely opened.

A rotary hinge type repulsion structure is adopted between the static contact 1 and the moving contact 2. The metal strip of the static contact at least comprises a straight section parallel to the moving contact, the direction of current in the straight section is opposite to that of current in the moving contact, and the length of the straight section is more than or equal to the length required by repulsion force generated when short-circuit current flows through the moving contact and the static contact to repel each other. When a short-circuit fault occurs, short-circuit current in opposite directions flows through the static contact straight section and the moving contact, and at the moment, repulsion is generated between the static contact and the moving contact, so that the moving contact 2 rotates clockwise around the rotating shaft A of the moving contact to repel.

In the invention, insulation arc extinguishing devices are designed and installed at the positions of a static contact 1 and a moving contact 2, the static and moving contacts can also be of a repulsion structure without parallel opposite currents, and when the moving contact acts under the driving of a magnetic protection release 10 and a tripping mechanism 10-1 in the short-circuit breaking process of the MCCB, an insulation shielding plate 4 can also be rapidly inserted between the static and moving contacts, thereby achieving the purpose of rapid insulation shielding arc extinguishing.

The arc extinguishing chamber 13 is used for quenching the residual arc by cooling, so that the capacity thereof can be suitably reduced; a handle 14 is mounted on the upper end of the housing 12 for normal switching on and off operation.

Due to the technical scheme adopted by the MCCB, the following technical progress can be obtained:

1, the capacity of breaking short-circuit current of a product can be greatly improved;

2. the purpose of alternating current and direct current is achieved;

3. when the fault short-circuit current is cut off, the further expansion of the arc energy can be limited, so that short arcing or no arcing of the product can be realized.

Claims

1. A molded case circuit breaker with composite arc extinguishing performance comprises a static contact (1), a moving contact (2), a magnetic protection release (10), a tripping mechanism (10-1) and an arc extinguishing chamber (13) which are arranged in an engineering plastic shell (12), and is characterized in that an insulating arc extinguishing device is additionally arranged, the insulating arc extinguishing device comprises a magnetic yoke (3), an armature (5), an insulating shielding plate (4), a swing rod (7) and a supporting seat (8), the magnetic yoke (3) and the supporting seat (8) are both fixed on the static contact (1), and the supporting seat (8) is positioned below the magnetic yoke (3); the insulation shielding plate (4) is positioned on one side of the static contact (1) and corresponds to a gap between the static contact (1) and the moving contact (2); the upper ends and the lower ends of the swing rod (7) and the magnetic yoke (3) are respectively rotatably connected with the insulating shielding plate (4) and the supporting seat (8), the swing rod (7), the armature (5), the insulating shielding plate (4) and the supporting seat (8) form a four-bar structure, and a torsion spring (6) is arranged between the armature (5) and the supporting seat (8);

the two sides of the insulation shielding plate (4) are bent downwards, one end, far away from the magnet yoke (3), of the bent portion is rotatably connected with the armature (5), and one end, close to the magnet yoke (3), of the bent portion is rotatably connected with the swing rod (7).

2. The molded case circuit breaker with composite arc extinguishing performance according to claim 1, wherein an insulating gasket (9) is arranged between the magnetic yoke (3) and the static contact (1).

3. The molded case circuit breaker with composite arc extinguishing performance according to claim 2, wherein the swing link (7) is provided in two, and the two are symmetrically installed at both sides of the insulation shielding plate (4) and the supporting seat (8).